It could be something else but also it’s a sign of being chased. Hope things turn around for him.So I put mirrors on both sides of the tank to keep the lyertail active killing itself. Will leave it up for a week or two. I don't want to go overly crazy as I think something is off with this exqusite. It hasn't left the corner of the overflow in 3 weeks. It's almoat.like it has a swim bladder issue or something. It only skims the surface and hangs vertically. Each day it is out less and less.